Methods for encoding decoding of a data flow representing of an omnidirectional video

Abstract

A method for encoding a data stream representing an omnidirectional video. The method includes: encoding, in the stream, at least one base layer representative of a 2D or 3D video, the 2D or 3D video being representative of a view of a same scene captured by the omnidirectional video; and encoding, in the stream, one enhancement layer representative of the omnidirectional video. The enhancement layer is encoded by prediction relative to the base layer. The prediction of the enhancement layer relative to the base layer includes: generating a reference sub-image obtained by geometrical projection on the reference sub-image of an image, called a base image, rebuilt from the base layer, and storing the reference sub-image in association with shift information enabling an encoder to determine the location of the reference sub-image in the enhancement image in a non-transitory computer-readable memory of reference sub-images of the enhancement layer.

What is claimed is: 
     
       1. A method for encoding a data stream representative of an omnidirectional video, wherein the method comprises the following acts performed by an encoding device:
 encoding, in said stream, at least one base layer representative of a 2D or 3D video, the 2D or 3D video being representative of a view of a same scene captured by the omnidirectional video; and 
 encoding, in said stream, one enhancement layer representative of the omnidirectional video, the enhancement layer being encoded by prediction relative to the at least one base layer, 
 
       wherein the prediction of the enhancement layer relative to the at least one base layer comprises, in order to encode one image of the enhancement layer, called enhancement image, for each of said at least one base layer:
 generating a reference sub-image obtained by geometrical projection on said reference sub-image of an image, called a base image, rebuilt from said base layer, said reference sub-image serving as a prediction for said at least one enhancement image, 
 storing said reference sub-image in association with shift information enabling an encoder to determine the location of the reference sub-image in the enhancement image in a non-transitory computer-readable memory of reference sub-images of the enhancement layer. 
 
     
     
       2. The method according to  claim 1 , wherein the data stream comprises a piece of information representative of a type of a geometrical projection used to represent the omnidirectional video. 
     
     
       3. The method according to  claim 1 , wherein the view represented by the 2D or 3D video is a view extracted from the omnidirectional video. 
     
     
       4. The method according to  claim 3 ,
 wherein the data stream comprises a piece of information representative of parameters of projection and of location of said base image in an image of the omnidirectional video, said information being used to project the base image on the reference sub-image. 
 
     
     
       5. The method according to  claim 4 , wherein said piece of information representative of the parameters of projection of location of said base image is encoded in the data stream at each image of the omnidirectional video. 
     
     
       6. A method for decoding a data stream representative of an omnidirectional video, wherein the method comprises the following acts performed by a decoding device:
 decoding, from said stream, at least one base layer representative of a 2D or 3D video, the 2D or 3D video being representative of a view of a same scene captured by the omnidirectional video, 
 decoding, from said stream, one enhancement layer representative of the omnidirectional video, the enhancement layer being decoded by prediction relative to the at least one base layer, 
 
       wherein the prediction of the enhancement layer relative to the at least one base layer comprises, in order to decode one image of the enhancement layer, called enhancement image, for each of said at least one base layer:
 generating a reference sub-image obtained by geometrical projection on said reference sub-image of an image, called a base image, rebuilt from said base layer, said reference sub-image serving as a prediction for said at least one enhancement image, 
 storing said reference sub-image in association with shift information enabling a decoder to determine the location of the reference sub-image in the enhancement image in a non-transitory computer-readable memory of reference sub-images of the enhancement layer. 
 
     
     
       7. The method according to  claim 6 , wherein the data stream comprises a piece of information representative of a type of a geometrical projection used to represent the omnidirectional video. 
     
     
       8. The method according to  claim 6 , wherein the view represented by the 2D or 3D video is a view extracted from the omnidirectional video. 
     
     
       9. The method according to  claim 8 ,
 wherein the data stream comprises a piece of information representative of parameters of projection and of location of said base image in an image of the omnidirectional video, said information being used to project the base image on the reference sub-image. 
 
     
     
       10. The method according to  claim 9 , wherein said piece of information representative of the parameters of projection of location of said base image is encoded in the data stream at each image of the omnidirectional video. 
     
     
       11. The method according to  claim 6 , wherein the data stream comprises at least two base layers, each base layer being representative of a 2D or 3D video, respectively representative of a view of the scene, the at least two base layers being encoded independently of each other. 
     
     
       12. A device for encoding a data stream representative of an omnidirectional video, wherein the device comprises:
 a processor; and 
 a non-transitory computer-readable medium comprising instructions stored thereon, which when executed by the processor configure the device to: 
 encode, in said stream, at least one base layer representative of a 2D or 3D video, the 2D or 3D video being representative of a view of a same scene captured by the omnidirectional video; and 
 encode, in said stream, one enhancement layer representative of the omnidirectional video, the enhancement layer being encoded by predicting the enhancement layer relative to the at least one base layer, 
 
       wherein the prediction of the enhancement layer relative to the at least one base layer comprises, in order to encode one image of the enhancement layer, called enhancement image, for each of said at least one base layer:
 generating a reference sub-image obtained by geometrical projection on said reference sub-image of an image, called a base image, rebuilt from said base layer, said reference sub-image serving as a prediction for said at least one enhancement image, 
 storing said reference sub-image in association with shift information enabling an encoder to determine the location of the reference sub-image in the enhancement image in a non-transitory computer-readable memory of reference sub-images of the enhancement layer. 
 
     
     
       13. A device for decoding a data stream representative of an omnidirectional video, the device comprises:
 a processor; and 
 a non-transitory computer-readable medium comprising instructions stored thereon, which when executed by the processor configure the device to: 
 decode, in said stream, at least one base layer representative of a 2D or 3D video, the 2D or 3D video being representative of a view of a same scene captured by the omnidirectional video; and 
 decode, in said stream, one enhancement layer representative of the omnidirectional video, the enhancement layer being decoded by prediction relative to the at least one base layer, 
 
       wherein the prediction of the enhancement layer relative to the at least one base layer comprises, in order to decode one image of the enhancement layer, called enhancement image, for each of said at least one base layer:
 generating a reference sub-image obtained by geometrical projection on said reference sub-image of an image, called a base image, rebuilt from said base layer, said reference sub-image serving as a prediction for said at least one enhancement image, 
 storing said reference sub-image in association with shift information enabling a decoder to determine the location of the reference sub-image in the enhancement image in a non-transitory computer-readable memory of reference sub-images of the enhancement layer. 
 
     
     
       14. A non-transitory computer-readable medium comprising instructions stored thereon, which when executed by a processor of an encoding device or respectively a decoding device configure the encoding device or respectively the decoding device to:
 encode or respectively decode a data stream representative of an omnidirectional video by: 
 encoding or respectively decoding, in said stream, at least one base layer representative of a 2D or 3D video, the 2D or 3D video being representative of a view of a same scene captured by the omnidirectional video; and 
 encoding or respectively decoding, in said stream, one enhancement layer representative of the omnidirectional video, the enhancement layer being encoded by prediction relative to the at least one base layer, 
 
       wherein the prediction of the enhancement layer relative to the at least one base layer comprises, in order to encode at image of the enhancement layer, called enhancement image, for each of said at least one base layer:
 generating a reference sub-image obtained by geometrical projection on said reference sub-image of an image, called a base image, rebuilt from said base layer, said reference sub-image serving as a prediction for said at least one enhancement image, 
 storing said reference sub-image in association with shift information enabling the encoding device or the decoding device to determine the location of the reference sub-image in the enhancement image in a non-transitory computer-readable memory of reference sub-images of the enhancement layer.